JP3893459B2 - Magnesium oxide nanobelts and composites thereof, and methods for producing them - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention of this application relates to a magnesium oxide nanobelt and a composite thereof, and a production method thereof. More specifically, the invention of this application relates to a magnesium oxide nanobelt having a size that can be applied to electrical and optical devices, a composite thereof, and a method of manufacturing the same.
[0002]
[Prior art]
Oxide nanobelts, which are a new kind of linear nanomaterials, are expected to be used as valuable units that can be used to set the shape and dimensions of nanodevices that are expected to be promising in the future, as well as electrical and optical devices. Application to is promising. So far, nanobelts with different configurations, such as zinc oxide, tin oxide, indium oxide, gallium oxide, etc., have been synthesized by several research groups.
[0003]
By the way, magnesium oxide is an insulator having a wide band gap that exhibits high secondary electron emission. The emission of secondary electrons from solids is important for devices such as electron microscopes, and is important in reducing discharge voltage in order to increase the electrical efficiency of plasma display panels. For this reason, magnesium oxide films are generally used in plasma display panels to obtain a protective layer for surface resistivity and a high secondary electron emission coefficient. Recently, fishbone-like magnesium oxide nanorods and nanobelts have been synthesized by a common catalytic process (for example, Non-Patent Document 1) or by heating magnesium chloride in an oxygen-flowing environment (for example, Non-Patent Document 2).
[0004]
[Non-Patent Document 1]
YQ Zhu, 5 others, Chem. Phys. Lett., 2001, Vol. 347, p. 337
[Non-Patent Document 2]
J. Zhang, 3 others, Applied Phys. A, 2001, Vol. 73, p. 773
[0005]
[Problems to be solved by the invention]
However, a technique for generating linear magnesium oxide nanostructures dispersed in the same shape over a wide range on a certain substrate has not been established. Therefore, realization is desired from the viewpoint of practical application.
[0006]
The invention of this application has been made in view of such circumstances, and provides a magnesium oxide nanobelt having a size that can be applied to an electrical and optical device, a composite thereof, and a method for producing the same. It is a problem to be solved.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the invention of this application is to form a network structure by connecting individual magnesium oxide nanobelts in a single crystal and linearly with neighboring magnesium oxide nanobelts in a T shape or a cross shape. The present invention provides a magnesium oxide nanobelt (claim 1).
[0008]
The invention of this application relates to the invention according to claim 1, wherein each magnesium oxide nanobelt has a length of 5 μm or less, a width of 100 nm to 200 nm, and a ratio of the width to the thickness of 1 to 1. (Claim 2) is provided as an embodiment.
[0009]
Further, according to the invention of this application, the magnesium oxide nanobelt according to claim 1 or 2 is irregularly dispersed on any one of a silicon substrate, a molybdenum substrate, and a tantalum substrate and grown in a film shape. A magnesium oxide nanobelt composite characterized in that (Claim 3) is provided.
[0010]
Furthermore, in the invention of this application, magnesium powder and aluminum powder are mixed at a weight ratio of 1: 1, and a press-formed metal disk is used as a target material, and the metal disk is drilled in a reaction furnace. Placed above the tantalum holding plate, and below the tantalum holding plate, any one of silicon wafer, molybdenum wafer or tantalum wafer is placed, the inside of the reactor is depressurized to 0.1 torr or less, and the metal disc Is heated from 900 ° C. to 1000 ° C. for 1 hour from the upper surface, and then cooled to room temperature to produce the magnesium oxide nanobelt or the magnesium oxide nanobelt composite according to claim 1, 2 or 3. A method for producing a magnesium oxide nanobelt or a magnesium oxide nanobelt composite is provided.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The invention of this application has the features as described above. Hereinafter, the examples will be described, and the magnesium oxide nanobelt of the invention of this application, its composite, and the production method thereof will be described in more detail.
[0012]
【Example】
Magnesium powder and aluminum powder (100 mesh, purity greater than 99.99%) were mechanically mixed at a weight ratio of 1: 1 and press-molded to produce a metal disk (φ10 mm × 2 mm). This metal disk was used as a target material and placed in a high vacuum infrared irradiation heating furnace as a reaction furnace. In the high-vacuum infrared irradiation heating furnace, the metal disk was placed above the tantalum holding plate with a hole of φ9 mm. Further, a mirror-finished silicon wafer was disposed at a position 2 mm below the tantalum holding plate. Then, the chamber was depressurized to 0.1 torr or less, and the metal disk was rapidly heated to 950 ° C. from its upper surface. At this time, the silicon wafer was heated to 650 ° C to 700 ° C. Heating was continued for 1 hour, after which the chamber was cooled to room temperature. The upper surface of the silicon wafer was covered with a white film. The form of the formed film was observed with a manipulation electron microscope (SEM).
[0013]
FIGS. 1A and 1B are scanning electron microscope images of the obtained films, respectively. SEM observations show that all silicon wafer surfaces are covered by irregularly dispersed nanobelts. Each nanobelt has a length of 5 μm or less, a width in the range of 100 nm to 200 nm, and a width to thickness ratio of 1 to 2. FIG. 1B shows that individual nanobelts are connected to neighboring nanobelts to form a complex network-like nanostructure.
[0014]
2A, 2B, and 2C are images of network nanostructures, respectively. FIG. 2 (a) shows a simple network formed by two parallel nanobelts and short bridges. FIG. 2B shows a network connected in a T shape and a cross shape. FIG. 2 (c) shows the frame closed in a high pressure state.
[0015]
3A and 3B are a transmission electron microscope (TEM) image and an EDS spectrum of the nanobelt, respectively. In FIG. 3A, a nanobelt having a square cross section is clearly shown. As a result of EDS microanalysis, as shown in FIG. 3 (b), it was confirmed that all nanobelts were composed of magnesium and oxygen (atomic ratio is 1: 1), and a pure magnesium oxide phase was formed. It was. Aluminum element was not detected. The peak corresponding to the Cu (copper) element in FIG. 3B is generated from the copper lattice used for transmission electron microscope (TEM) observation.
[0016]
4A and 4B are high-resolution transmission electron microscope (HRTEM) images, respectively, and the inset is an electron diffraction (ED) pattern. 4 (a) and 4 (b), it is confirmed that the magnesium oxide nanobelt is a cubic single crystal with a lattice-shaped arrangement of a = 4.21Å.
[0017]
When it replaced with a silicon wafer and carried out similarly using a molybdenum wafer and a tantalum wafer, the same result as the above silicon wafer was obtained.
[0018]
Of course, the invention of this application is not limited by the above embodiments. Needless to say, various details are possible.
[0019]
【The invention's effect】
As described in detail above, the invention of this application provides a magnesium oxide nanobelt and a composite thereof having a sufficient size applicable to electrical and optical devices.
[Brief description of the drawings]
FIGS. 1A and 1B are scanning electron microscope images of films obtained in Examples, respectively.
FIGS. 2A, 2B, and 2C are images of network nanostructures obtained in Examples. FIG.
FIGS. 3A and 3B are a transmission electron microscope (TEM) image and an EDS spectrum of the nanobelt obtained in Example, respectively.
4A and 4B are high-resolution transmission electron microscope (HRTEM) images, respectively, and the inset is an electron diffraction (ED) pattern.

Claims (4)

A magnesium oxide nanobelt characterized in that a single crystal and linear individual magnesium oxide nanobelt is connected to a neighboring magnesium oxide nanobelt in a T shape or a cross to form a network. 2. The magnesium oxide nanobelt according to claim 1, wherein each magnesium oxide nanobelt has a length of 5 μm or less, a width of 100 nm to 200 nm, and a width to thickness ratio of 1 to 2. 3. The magnesium oxide nanobelt according to claim 1 or 2, wherein the magnesium oxide nanobelt is irregularly dispersed on any one of a silicon substrate, a molybdenum substrate, and a tantalum substrate, and grows in a film shape. Belt composite. Magnesium powder and aluminum powder are mixed at a weight ratio of 1: 1, and a press-formed metal disc is used as a target material, and the metal disc is placed above the tantalum holding plate with holes in the reactor. Then, below the tantalum holding plate, one of silicon wafer, molybdenum wafer or tantalum wafer is placed, the inside of the reactor is depressurized to 0.1 torr or less, and the metal disk is placed at 900 ° C. to 1000 ° C. from its upper surface. A magnesium oxide nanobelt or a magnesium oxide nanobelt characterized in that the magnesium oxide nanobelt or the magnesium oxide nanobelt composite according to claim 1, 2 or 3 is produced by heating to ° C for 1 hour and then cooling to room temperature. A method for producing a composite.

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